Can't help with source but it would make sense to add them if you have wire wheels. They act like a fan in heavy rain throwing water onto the discs which then causes a short delay before full braking effect is acheived.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
